The video resource "Reproductive System, part 1 - Female Reproductive System: Crash Course A&P #40" is included in the "Anatomy & Physiology " course from the resources series of "Crash Course". Crash Course is a educational video series from John and Hank Green.

The video resource "Reproductive System, part 2 - Male Reproductive System: Crash Course A&P 41" is included in the "Anatomy & Physiology " course from the resources series of "Crash Course". Crash Course is a educational video series from John and Hank Green.

The video resource "Reproductive System, part 3 - Sex & Fertilization: Crash Course A&P #42" is included in the "Anatomy & Physiology " course from the resources series of "Crash Course". Crash Course is a educational video series from John and Hank Green.

The video resource "Reproductive System, part 4 - Pregnancy & Development: Crash Course A&P #43" is included in the "Anatomy & Physiology " course from the resources series of "Crash Course". Crash Course is a educational video series from John and Hank Green.

Watch as the heart cells use energy to reset the concentration gradients for all of the ions after the action potential has gone through. Rishi is a pediatric infectious disease physician and works at Khan Academy.

Learn how the size of a tube (it's radius) is related to its resistance to something flowing through. Rishi is a pediatric infectious disease physician and works at Khan Academy.

Find out how the respiratory center collects information from all over the body and then helps regulate your breathing. Rishi is a pediatric infectious disease physician and works at Khan Academy. These videos do not provide medical advice and are for informational purposes only. The videos are not intended to be a substitute for professional medical advice, diagnosis or treatment. Always seek the advice of a qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read or seen in any Khan Academy video.

Paul Andersen starts this video with a description of the respiratory surface. He explains how worms, insects, fish and mammals take in oxygen and release carbon dioxide. He then tours the major organs of the respiratory system, from the pharynx to the trachea, bronchus, bronchiole and alveoli.

The video resource "Respiratory System, part 1: Crash Course A&P #31" is included in the "Anatomy & Physiology " course from the resources series of "Crash Course". Crash Course is a educational video series from John and Hank Green.

The video resource "Respiratory System, part 2: Crash Course A&P #32" is included in the "Anatomy & Physiology " course from the resources series of "Crash Course". Crash Course is a educational video series from John and Hank Green.

Paul Andersen explains how organisms respond to the external environment. He begins with a discussion of behavioral responses like hibernation and migration. He ends with a discussion of physiological responses like shivering and sweating. Organisms respond to their environment in order to maintain homeostasis.

This "The Resting Membrane Potential" learning object is the from the Sumanas resource series. Sumanas offers a robust selection of content and services that are directed at enhancing the learning experience.

Restore America's Estuaries describes the importance of estuaries as nurseries for ocean life and other ecosystems. It also outlines how we can work together to save and develop these important ecosystems.

The discovery of restriction enzymes and their applications in DNA analysis has proven to be essential for biologists and chemists. This lesson focuses on restriction enzymes and their applications to DNA analysis and DNA fingerprinting. Use this lesson and its associated activity in conjunction with biology lessons on DNA analysis and DNA replication.

Paul Andersen reviews the major concepts within the fourth unit of the new AP Biology framework. He begins by differentiating between negative and positive feedback loops. He explains how a stable internal environment is maintained through behavior and physiology. He details thermoregulation, osmoregulation and blood glucose regulation.

Paul Andersen reviews the major within the first unit on natural selection. He starts by defining evolution and explaining how evolution can occur in a population. He reviews the population genetics and camouflage lab.

Paul Andersen reviews the major concepts within the second unit of the new AP Biology framework. He starts by describing how life is organized into three domains. He explains how the history of life on the planet is characterized by mass extinctions followed by adaptive radiation.

Students build on their understanding and feel for flow rates, as gained from the associated Faucet Flow Rate activity, to estimate the flow rate of a local river. The objective is to be able to relate laboratory experiment results to the environment. They use the U.S. Geological Survey website (http://waterdata.usgs.gov/nwis/rt) to determine the actual flow rate data for their river, and compare their estimates to the actual flow rate. For this activity to be successful, choose a nearby river and take a field trip or show a video so students gain a visual feel for the flow of the nearby river.

Role of phagocytes in innate or nonspecific immunity. Neutrophils, macrophages, and dendritic cells. MHC II.

The role of the sarcoplasmic reticulum in controlling calcium ion concentrations within the muscle cell